I don't know a easy way to test this type of program. I can imagine making a something similar to a facade pattern that replaces the API you are using to log and test the student's program behavior. But I also think it may be a hard and fragile way to test student's programs.
Best regards,
Juan Carlos.

I'm not sure it's worth mentioning, I've modified locally the vpl_evaluate.cpp to cope with dot '.' in program output compared to expected output in vpl_evaluate.cases Else, punctuation ("Hi.") is confused with numbers (".5").
Here some explanation with a short example.
Suppose we want to test a program "+1" with the test.case :

Hello Dan Nguyen Duc,
Install the third party package on the jail server and restart the service.
You also can add files to specific activities as "execution files" and remember to mark the files as "Files to keep when running".

Thank you Juan Carlos,
- add files to specific activities as "execution files" and remember to mark the files as "Files to keep when running": Ok - Done, but
- Install the third party package on the jail server and restart the service: Not done. In my server, i added third party to default package of Python, and test success on server when call function of third party.

Hi
I have created the Jail Server but when I try to connect to the server via https I get a warning about the certificate, and then a 404 error. Does this mean that the server is being contacted but that the jail server software itself is not installed correct, or is this not an assumption I can make (that the certificate notification is not evidence of a successful connection to the physical server or URL)?

When I log in to the server via PuTTY and go to the root of the directory structure I can see a directory called jail; is this where it should be residing?

Sorry but not yet getting any OK message and trying to identify why not.

Hello Oleksandr Szpinkowski,
I have searched about IDP assuming that it is "Intel® Distribution for Python". It seem a tool for accelerate Python on Intel's processors, notice that VPL is a learning tool. Really I dont know if the restrictions of the VPL excution server allow to execute the accelerated Python but you can try.
1) Install the IDP on a "Execution server" following the IDP home site instructions on how to install it on linux.
2) Restart the "Execution server"
3) Go to "Execution files" on a VPL activity and copy the default Python into vpl_run.sh and change it properly to use IDP instead of python3https://github.com/jcrodriguez-dis/moodle-mod_vpl/blob/v3.3.2/jail/default_scripts/python-3_run.sh